The S&P 500 has ended at its lowest level since early May after technology and internet shares sold off further, capping a volatile week that confirmed a correction for the Nasdaq.

The benchmark S&P 500 itself flirted with correction territory - when an index closes 10 per cent or more below its all-time closing high - but recovered to end off that level.

Grim results from Amazon.com and Google-parent Alphabet, two stocks that have helped power the equity markets decade-long bull run, sparked the day's sell-off and overshadowed data showing the US economy continued to grow at a healthy clip.

"It's all been driven off quarter reporting," said Ernesto Ramos, portfolio manager for BMO Global Asset Management in Chicago.

"When the reports are bad in technology you get a really bad day because of the elevated valuations."

Investors may see more volatility through the remainder of the US earnings season and ahead of the November 6 US midterm congressional elections, he and other money managers said.

"Once the elections and earnings are out of the way, we'll have a calmer market but not necessarily a big move up," Ramos said.

Alphabet's revenue missed estimates, fanning concerns that regulatory scrutiny and competition would throttle its scorching pace of growth. The stock fell as much as 5.6 per cent before recovering to end down just 1.8 per cent.

Amazon tumbled 7.8 per cent in its worst daily percentage drop since October 2014, after it missed quarterly sales estimates and gave a below par holiday-season sales forecast.

The Dow Jones Industrial Average fell 296.24 points, or 1.19 per cent, to 24,688.31, the S&P 500 lost 46.88 points, or 1.73 per cent, to 2,658.69 and the Nasdaq Composite dropped 151.12 points, or 2.07 per cent, to 7,167.21.

The S&P 500 finished at its lowest level since May 3. The Nasdaq fell 3.8 per cent for the week, its biggest weekly drop since March 23, while the Dow was down 3 per cent and the S&P 500 was down 4 per cent on the week.

While economic growth is mostly healthy, disappointing corporate results and forecasts this earnings season have shown how tariffs, rising wages and borrowing costs as well as jitters over geopolitical events are hurting companies.

Data earlier in the day showed the US economy continued to grow at a healthy pace, offering some support.

US gross domestic product growth slowed less than expected in the third quarter as a tariff-related drop in soybean exports was partially offset by the strongest consumer spending in nearly four years and a surge in inventory investment.

The Cboe Volatility Index, the most widely followed gauge of expected near-term gyrations for the S&P 500, finished little changed at 24.16.